Most known electric toothbrushes utilize a single bristle carrier that is powered or otherwise driven by an electric motor incorporated in the toothbrush. The bristle carriers in these toothbrushes generally undergo rotary motion. Although satisfactory in certain respects, a need still exists for an improved powered toothbrush design.
Numerous attempts have been made to improve the design, efficiency, cleaning efficacy, simplicity, and/or commercial viability of electric toothbrushes. One approach has been the provision of multiple powered bristle carriers. Most artisans have grouped multiple sets of bristles along an end of a brush and incorporated a drive mechanism for simultaneously rotating each of the bristle sets, together. Exemplary designs include those disclosed in U.S. Pat. Nos. 3,242,516; 4,156,620; 4,845,795; 5,088,145; 5,020,179; 4,827,550; and 4,545,087.
A related strategy is to group sets of bristles on multiple rotating bristle carriers, as disclosed in U.S. Pat. Nos. 2,140,307 and 5,170,525. Rather than rotating each individual bristle set about its center, i.e. the approach adopted in the previously noted patents, the designs described in the '307 and '525 patents rotate multiple groups of bristle sets about the center of a bristle carrier. Specifically, multiple groups of bristle sets are disposed on a circular bristle carrier and that bristle carrier, typically one of several, is rotated about its own axis.
U.S. Pat. No. 5,070,567 describes a design combining the two previously noted strategies. A rotating bristle carrier is provided along with multiple individually rotatable bristle sets. Although this design likely provides many of the advantages associated with each of its predecessors, the cleaning efficacy of spinning bristle sets, alone, is somewhat limited.
Yet another design is disclosed in U.S. Pat. No. 5,617,603. The '603 patent describes an assembly of “staggered swing” brushes. Apparently, the two bristle carriers move along a complex path within the plane of the toothbrush.
Although dual bristle carriers that undergo various combinations of movement have been disclosed in the prior art, there remains a need to provide an electric toothbrush with a plurality of bristle carriers in which at least one carrier undergoes a reciprocating or pivotal type of motion. Additionally, there is a need to provide an electric toothbrush with multiple bristle carriers in which at least one of the carriers reciprocates while another component of the brush undergoes a particular type of motion that assists in the brushing operations.